Structural components of a motor vehicle that are electrical conductors, such as metal of the body and the chassis frame, form the electrical ground for the vehicle's electrical system. Motor vehicles that operate on roads and highways typically have an occupant compartment, where the driver and any passenger or passengers sit, and in front of the occupant compartment, an engine compartment for housing the engine that propels the vehicle. In a large truck, the occupant compartment is commonly called the cab.
A dash panel that is part of a truck cab separates the cab interior from the engine compartment. A known practice for grounding at least some engine compartment circuits and at least some occupant compartment circuits to the vehicle's ground comprises grounding the circuits through a ground block that is mounted on the dash panel at a pass-through.
A typical ground block has a base that is disposed against the dash panel on either the engine compartment side or the cab side and fastened to the dash panel. One or more studs project from the base, either toward the engine compartment or toward the occupant compartment. If the base is disposed against the cab side of the dash panel, one or more studs project through one or more respective holes in the dash panel and into the engine compartment. If the base is disposed against the engine compartment side of the dash panel, the one or more studs project through one or more holes in the dash panel and into the cab interior. The ground block may also comprise one or more studs that project away from a surface of the base that is opposite the surface that is disposed against the dash panel.
The terminal of one or more electrical ground wires or ground cables is located to a stud of the ground block and a nut on the stud is tightened down against the one or more terminals thereby grounding the wires and cables to the ground block. Where studs are present on both engine compartment and cab sides, both cab circuit ground wires or cables and engine circuit ground wires or cables can be connected in common at the ground block.
Because many body panels of a truck cab, like the dash panel, are steel, and because steel is an electrical conductor, the contact between the dash panel and the mounted ground block grounds both engine compartment and cab grounds to the cab body.
Because it is desirable that good electrical contact be established between the ground block and the dash panel, and because certain truck cabs are pre-painted before the ground block is mounted on the dash, it is necessary that the paint and the primer or undercoat be removed from the area of the dash surrounding the pass-through hole, or holes, for a grounding block stud, or studs, before the ground block is mounted.
This stripping of insulated matter from the underlying conductor is typically performed by a mechanical action on an assembly line, such as by applying a wire wheel that is being spun by a power tool to the painted surface to abrade the paint and the primer or undercoat until bare metal is exposed.
That procedure however creates dust and exposes the bare metal to possible rusting. Because it is also difficult to control the amount of paint and undercoat being stripped, the process is to some degree inherently inconsistent from truck to truck.
The inventor believes that the process of assuring good conductivity between the ground block and the dash panel can be greatly improved by using a different process that doesn't involve removal of the paint and undercoat by mechanical abrasion.